Barrel engine pistons



arch 25, 1969 H. H. HAMLIN BARREL ENGINE PISTONS Filed Sept. 22, 1967Sheet of 2 INVENTOR. HALLEY H. l/QML/ a M Gab-.2 5.

II /arm? 35 March 25, 1969 H. H. HAMLIN I 3,434,397

BARREL ENGINE PI STONS Filed Sept. 22, 1967 Sheet 2 of2 Figo 2.

INVENTOR. H/uwy h. HnMu/v F3 5 M United States Patent O U.S. C]. 92-71 2Claims ABSTRACT OF THE DISCLOSURE A piston for a barrel engine having areduced diameter portion adaptable for reciprocating in a cylinder andhaving an enlarged diameter portion having first and second rollersattached thereto which are engageable with the top and bottom sides,respectively, of a harmonic cam on an output shaft. Guide shoes attachedto the cylinder slidably engage a longitudinal slot in the enlargeddiameter portion of the piston toprevent rotation of the piston.

The following pending applications of applicant are related to thepresent disclosure:

(a) Application Ser. No. 538,162, filed Mar. 22, 1966, for SealingDevice for High Temperature Input Nozzle;

(b) Application Ser. No. 546,150, filed Apr. 26, 1966, for Barrel EngineHaving Cooling System; and

Application Ser. No. 547,080, vfiled Apr. 29, 1966, now Patent No.3,359,864, for Barrel Engine Having Forced Lubrication.

Background of the invention The present invention relates to improvedpistons for a barrel engine. A barrel engine is an engine that has aplurality of pistons having their stroke axes parallel to andsymmetrically disposed to a power output shaft. The pistons coact withcam means on the output shaft so as to convert the reciprocating motionof the pistons into rotary motion which rotates the output shaft. Barrelengines may find application in many fields both commercial andmilitary, and one important military application for a barrel engine isthat of a propulsion unit for Naval torpedoes.

One heretofore known barrel engine specifically adaptable for use as aprime mover for Naval torpedoes is disclosed in the present inventor'sUS. Patent 3,151,527, entitled Barrel Engine, which issued Oct. 6, 1964.In this patent, there is disclosed a barrel engine having torquebalanced contra rotating propellers for propelling a torpedo throughwater. Torque balance is required since a lack of its would impose aresisting torque on the torpedo body and cause the torpedo to roll toone side. A permanent inclination o fthe torpedo is very undesirable asit will interfer with the steering controls. An outer housing and ahollow inner shaft are coaxially mounted relative to each other andadapted to establish relative rotation. A fluid pressure inlet, throughwhich hot gas flows, is positioned coaxially with respect to the innershaft. The motive power assembly includes a plurality of pistonsreciprocally mounted in the housing with their stroke axes parallel tothe axial center of rotation. The motive power assembly isconstructioned and arranged to translate the fluid pressure into anaxial force component. A wobble plate conversion assembly is mounted tothe inner shaft for converting the reciprocatory substantially linearmotion of the pistons into rotary motion. The outer housing is rotatedin an opposite direction to the inner shaft solely by virtue of thereaction to the rotation of the inner shaft.

In applicants above-identified patent, a cylindrical piston is providedwith is of suitable annular dimension to 3 ,434,397 Patented Mar. 25,1969 slide within a cylinder casing. The piston has an integrated socketjoint receiving a sphere-like end of a piston rod member which connectsthe piston to a swashplate ring by way of a ball end portion which isreceived in a bronze ball socket joint. The outer cylindrical surface ofthe piston has a number of annular grooves which receive a metallic orplastic ring and one groove is adapted to receive an O-ring which servesto lend a certain degree of radial resiliency to the reciprocatingpiston member.

Summary of the invention The present invention relates to an improvementin barrel engines of the type shown in the inventors US. Patent3,151,527, and while the principle of operation is essentiallyidentical, there are some structural differences. For example, theswashplate cam of the patent, which serves to convert the reciprocatingmotion of the pistons to rotary motion which turns the inner tubularpower takeoif shaft, has been replaced by a harmonic cam.

The specific improvement for a barrel engine to which this disclosurerelates is that of the pistons which drive the harmonic cam which isattached to an inner output shaft. The piston has a reduced diameterportion that slides in a cylinder, and this reduced diameter portion isprovided with a plurality of grooves which are adapted to receive pistonrings. An enlarged diameter portion of the piston is provided with alongitudinal slot and a first roller is positioned in the slot androtatably mounted on a shaft which is attached to the enlarged diameterportion. A second roller is attached to the enlarged diameter portion ofthe piston, and the first roller transmits a heavy axial load imposedupon the reduced diameter portion of the piston by the working fluid toa harmonic cam which is attached to an output shaft. The second rollerengages the backside of the harmonic cam and serves to hold the pistonagainst inertia force during the exhaust stroke. A pair of guide shoesare provided on the cylinder walls and these guide shoe slidably engagewith the longitudinal slot in the enlarged diameter portion to preventrotation of the piston.

It is therefore a general object of the present invention to provide ina barrel engine an improved mechanism for converting linear motion torotary motion by providing improved pistons which co-operate with aharmonic cam.

Other objects and advantages of the present invention will be readilyapperciated as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings.

Brief description 0] the drawings FIGURE 1 is a partial longitudinalsectional view showing an aft section of a torpedo which embodies thepresent invention;

FIGURE 2 is a partial longitudinal sectional view of a barrel engineembodying the present invention;

FIGURE 3 is a sectional view of a piston and a piston liner; and

FIGURE 4 is a sectional view taken on line 4-4 of FIGURE 3.

Description of the preferred embodiment Referring now to the drawings,and particularly to FIGURE 1, there is shown an aft section of a torpedohousing 11 in which a barrel engine 12 drives a pair of contrarotatingpropellers 13 and 14. Hot gas, or other suitable fluid, flows from acombustion chamber into barrel engine 12 where it is distributed to aplurality of cylinders by a rotary valve assembly. By way of example,the hot gas, or other suitable fluid, may flow from a combustion chamberinto a tubular conduit and a hot gas seal assembly, as shown inapplicants co-pending patent application entitled, Sealing Device forhigh Temperature Input Nozzle, which was filed Mar. 22, 1966, Ser. No.538,162. The hot gas enters into a rotary valve assembly whichdistributes the hot gas to the various cylinders.

The hot gas, or other suitable fluid, which is distributed by the rotaryvalve assembly to the various cylinders, drives pistons in the cylindersand the reciprocating motion of the pistons is converted into rotarymotion by means of a cam that is attached to and drives a hollow shaft15. Propeller 13 is attached on the end of hollow shaft 15 and isrotated thereby, and a second hollow shaft 16 is concentrically mountedaround hollow shaft 15 and is driven in a contra-rotating directionrelative to the direction of rotation of hollow shaft 15. Thereciprocatory linear motion of the pistons is converted, by the cam,into rotary motion which rotates the inner hollow shaft 15 and,simultaneously, torque reaction causes the outer hollow shaft 16 to becontrarotated, as shaft .16 is substantially integral with the housingof barrel engine 12. Propeller 14 is attached to the outer end of hollowshaft 16 and thus rotates in a contrarotating direction relative to thedirection of rotation of propeller 13.

Referring now to FIGURE 2 of the drawings, hollow shaft 15 is rotatablymounted within a housing by means of radial bearing 17 and thrustbearing 18. The housing is comprised of a front section 19 which isattached to an aft section 21 by means of bolts 22. By way of example,front section 19 might be comprised of a monolithic block of castaluminum. A cam 23 is attached to hollow shaft 15 by key 24, androtation of cam 23 causes a corresponding rotation of hollow shaft 15. Arotary valve 25, having an inlet port 26 and an exhaust port 27, isrotatably mounted in front housing section 19 and is attached to theinner end of hollow shaft 15. Exhaust port 27 communicates with the boreof hollow shaft 15 and exhaust products passing through port 27 passinto hollow shaft 15 and then are expelled into the air, or into thesea.

A plurality of cylinder liners 28 are seated one each in a plurality ofcylinder bores 29 and a reduced diameter portion 31 of a piston 32 isslidably mounted in each liner 28. A second liner 33 is also seated ineach cylinder bore 29 and the enlarged diameter portion 34 of piston 32slides in liner 33. As shown in FIGURES 2, 3, and 4 of the drawings, theenlarged diameter portion 34 of piston 32 is provided with alongitudinal slot 35 that divides enlarged diameter portion 34 into twolegs 36 and 37, with leg 37 being longer than leg 36. A main roller 38is positioned in slot 35 on shaft 39 that is fitted in legs 36 and 37.Spacers 41 and 42 are provided to reduce end play of roller 38. A secondroller 43 is attached to leg 37 by means of shaft 44 and nut 45. Mainroller 38 engages the front cam surface 46 of cam 23, and provides thedriving force from piston 32 to rotate shaft 15. 'Ilhe second roller 43engages the back cam surface 47 of cam 23 and holds piston 32 againstinertia forces during the exhaust stroke.

As best shown in FIGURES 3 and 4 of the drawings, a pair of guide shoes48 and 49 are attached to liner 33 to prevent piston 32 from rotating.The width of guide shoes 48 and 49 is such that the guide shoes slidablyengage with slot 35 in piston 32. One side of each guide shoe is shapedto fit the curvature of liner 33 and guide shoes 49 and 49 are attachedto liner 33, by way of example, with screws 51. The reduced diameterportion 31 of piston 32 is provided with grooves 52 which retain pistonrings 53.

In operation, hot gases enter rotary valve 25 from a stationary nozzleand these hot gases are selectively distributed to the various cylindersat an appropriate time when pistons 32 are in a position to make astroke. The hot gases impinge on the end of reduced diameter portion 31of piston 32 and move the piston outwardly. The

straight line motion of pistons 32 is converted to rotary motion bymeans of roller 38 which engages with the front cam surface 46 of cam23. As cam 23 is keyed to shaft 15, rotation of cam 23 causes shaft 15to be rotated in one direction, and shaft 16 is rotated in acontra-rotating direction due to torque reaction as more fully explainedby applicants U.S. Patent 3,151,527, entitled, Barrel Engine, whichissued Oct. 6, 1964.

It can thus be seen that the present invention provides an improvedpiston and cam arrangement for rotating a shaft of a barrel engine.Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood, that the invention may be practiced otherwise than asspecifically described.

I claim:

1. In a barrel engine having a housing, a hollow shaft rotatably mountedwithin said housing, a plurality of cylinder bores in said housingextending in circular array about said hollow shaft with their axesparallel thereto, said cylinder bores each having a reduced diameterportion and an enlarged diameter portion, and a harmonic cam attached tosaid hollow shaft, said harmonic cam having front and back carnsurfaces, the improvement comprising:

a plurality of pistons mounted one each in each said cylinder bore, eachsaid piston having a reduced diameter portion and an enlarged diameterportion respectively mounted in the reduced diameter portion andenlarged diameter portion of each said cylinder bore,

first and second rollers attached to each said enlarged diameter portionof each said piston, said first roller being engaged with said front camsurface and said second roller being engaged with said back cam surface,

said enlarged diameter portion of each said piston has a longitudinalslot extending substantially the entire length thereof whereby first andsecond legs are formed and wherein said first roller is rotatablyattached to said first and second legs in said longitudinal slot andwherein said second roller is rotatably attached to only said first leg,and

a pair of oppositely disposed guide shoes slidably engage with saidlongitudinal slot of each said enlarged diameter portion, said guideshoes being attached inside said cylinder bores.

2. In a barrel engine as set forth in claim 1 wherein each said reduceddiameter portion of each said piston is provided with a plurality ofgrooves adaptable for receiving sealing rings.

References Cited UNITED STATES PATENTS 1,299,477 4/1819 Kendall 911751,670,355 5/1928 Harris. 1,896,449 2/ 1933 Kreidler -56 2,083,510 6/1937Stigers 92-71 X 2,095,255 10/ 1937 Holmes 72-71 X 2,770,225 11/1956Palumbo 75-56 X 3,151,527 10/ 1964 Hamlin 91-175 3,153,986 10/1964Mitchell 92-33 FOREIGN PATENTS 844,129 4/ 1939 France.

EDGAR W. GEOGHEGAN, Primary Examiner.

I. C. COHEN, Assistant Examiner.

U.S. Cl. X.R. 91-175; 74-56; 92-172, 31

